The Black Death is far older than we thought
Cartography of Networks: Edition VII
Welcome to Cosmographia. This post is part of our Cartography of Networks series. For the full map of posts, see here.
In 1338, among a scattering of obscure villages just to the west of Lake Issyk-Kul, Kyrgyzstan, people began dropping dead in droves. Among the many headstones found in the cemeteries of Kara-Djigach and Burana, one can read epitaphs such as “This is the grave of Kutluk. He died of the plague with his wife.” Recently, ancient DNA exhumed from these sites has confirmed the presence of the plague bacterium Yersinia pestis, cause of the condition that became known as the Black Death. The strain detected in those remote graveyards of Central Asia has been identified as the most recent common ancestor of the plague that went on to kill as much as 60% of the Eurasian population in the great pandemic of the 14th-century.1
The bacterium spent six years creeping silently through the far-flung villages and towns of Central Asia, Yuan China, and down into India, leaving no trace in the historical record, but presumably leaving a trail of death in its wake. However, in 1344, an army marching south from Delhi was decimated by a “pestilence” before it ever reached its destination. In his journal, the Arab traveller Ibn Batutta described a sickness spreading through the southern Indian city of Madurai in the same year, writing, “Whoever caught it died on the morrow, or the day after.”
Rumours of a plague began to reach the Near East. The Arab historian Ibn al-Wardi wrote, “It began in the land of darkness… [and] it has been current for fifteen years… Plague sat like a king on a throne and swayed with power, killing daily one thousand or more and decimating the population. It destroyed mankind with its pustules… How amazingly does it pursue the people of each house! One of them spits blood, and everyone in the household is certain of death.”
In 1347, an army of the Golden Horde was besieging the Genoese trading colony of Caffa, on the Crimean peninsula, when a sickness rampaged through the camp. The contemporary Italian chronicler Gabriele de’ Mussis wrote of the deaths of “thousands upon thousands every day… [They] died as soon as the signs of disease appeared on their bodies: swellings in the armpit or groin caused by coagulating humours, followed by a putrid fever.” According to writers of the time, the increasingly desperate Mongol army, losing its strength hour by hour, turned to biological warfare and hurled the corpses of their dead over the city walls.2 When Genoese survivors of the battle fled in ships bound for Italy, they took the plague with them. Europe, with its densely populated cities, poor sanitation, and extensive trade networks, never stood a chance.
Millions perished all across the Old World, writhing in agony from the swollen buboes. As well as these lumps forming in their glands, internal bleeding turned the infected’s skin black, their lips and noses became gangrenous, and they couldn’t stop retching blood. If any of the pustules burst or were split, foul-smelling black pus and blood oozed out.
In Constantinople and Florence, at least half of the population perished. In Venice it was almost three-quarters. Fifty-six thousand people died in Marseille in a single month. Eight hundred people died a day in Paris, including Queen Joan of France. In Avignon, Pope Clement VI consecrated an enormous field so it could serve as a mass grave for sixty-two thousand dead. It didn’t take long for the pestilence to reach Britain and Ireland, where half of the population soon died. The Irish monk John Clynn, in his empty monastery, wrote that the Black Death had, “stripped villages, cities, castles, and towns of their inhabitants so thoroughly that there is scarcely anyone left alive in them… The whole world is encompassed by evil… I, waiting among the dead for death to come, have committed to writing what I have truly heard… I leave parchment for continuing the work, in case anyone should still be alive in the future.” Where these words end, the hand of another wrote, “Here, it seems, the author died.”
The ships crisscrossing the Mediterranean brought the sickness along with their goods bound for Egypt, the Levant, and Cyprus. The disease was soon travelling the caravan routes of Arabia, reaching Mecca in 1349 where it killed thousands. In the Asyut region of Upper Egypt, tax records show that the population collapsed from 6000 to 116 — a fall of 98%. “Cairo became an empty desert,” wrote Maqrizi, “and there was no one to be seen in the streets.”
Confused and terrified, those still living were desperate for an explanation for the calamity. A Parisian medical institution published a treatise blaming the alignment of “three planets in Aquarius,” which had caused a “deadly corruption of the air.” King Edward III of England was more biblical when he blamed the general wickedness of the people, while the Florentine Matteo Villani, wrote that, “It was thought that the people, whom God by grace had preserved in life, having seen the extermination of their neighbours… would become better, humble, virtuous… overflowing with love and charity for one another. But… the opposite happened.” In Germany and France, wild rumours circulated that the disease was caused by Jews poisoning the wells; the pogroms that ensued were vicious, with one report that “all the Jews between Cologne and Austria” were rounded up and burnt alive. The violence against European Jews became so bad that the Pope intervened and issued proclamations that forbid further attacks. Whether this made any difference or not is unclear.
By pandemic’s end, Europe lost at minimum one-third of its population, with the most conservative estimates putting the death toll at 25 million out of 75 million. “We have lost almost everything,” wrote the famous poet Petrarch, in a letter to a friend, “and found no rest… Last losses are beyond recovery, and death’s wound beyond cure. There is just one comfort: that we shall follow those who went before… The life we lead is a sleep; whatever we do, we dream. Only death breaks the sleep and wakes us from dreaming. I wish I could have woken before this.”
Of course, we now know that the primary vector of Yersinia pestis transmission was the fleas feasting upon the backs of rodents, like rats, or larger mammals like camels. Although the disease could be caught by touching or inhaling infected tissues, the primary route was via the fleas vomiting bacilli into the bloodstream before they commenced feeding on the host, or by the bacilli in their faeces coming into contact with cuts in the skin. Once in the blood, bacilli travelled through the body until they were intercepted by the lymph nodes, where they multiplied rapidly until they swelled, according to Boccaccio, to the size of apples or eggs.
Interestingly, the rural outbreaks seemed to have been more devastating than those in the cities, meaning that the key determinant in the spread was not the density of human hosts, but of rat colonies. Those that fled the urban centres for the apparent safety of the countryside found no respite among the villages and hamlets, where the death rate was often higher.
That the pandemic should have emerged from the Eurasian steppe should come as no surprise: it is one of the world’s great plague basins. The arid landscape lends itself perfectly to the spread of bacteria like Yersinia pestis, whose flea-hosts are prone to dramatic swings in reproductive rates with only small changes in environmental conditions like temperature and precipitation. Recent studies have revealed that just a single degree increase in temperature can lead to a 50% increase in plague prevalence in the great gerbil, the primary host rodent of the Central Asian steppes. Warmer springs and wetter summers lead to greater density in both the rodent and the flea populations, leading to a greater plague prevalence among them. Then when climatic conditions change, a subsequent drop in rodent numbers leads to an increased density of fleas per gerbil, increasing the likelihood that they look to jump to a new host, like humans.
In all, the Black Death pandemic of the 14th century raged across Eurasia for eight years, killing untold millions (50 million just in Europe), but, as it turns out, this was not the first time it had swept across the world.3
The first great bubonic plague in recorded history broke out some eight centuries before the medieval Black Death ravaged Europe.4 In the traditional story of this pandemic, as told by Byzantine chroniclers, the sickness had its origin in Ethiopia, then travelled up through trading barges of the Nile Delta, before reaching the port city of Pelusium in Egypt in 540 AD. From there it travelled, once more on the back of black rats hidden on grain ships, to Constantinople in 541 AD.
The Byzantine historian, Procopius of Caesarea, wrote that the plague was one “by which the whole human race came near to be annihilated.” The systems were the same as in the later outbreak — swollen buboes under the armpits and groins, septicaemia poisoning the blood. At its peak in the spring of 542, over 10,000 people were dying per day in Constantinople.
Both war and trade facilitated the spread of the bacterium across the Byzantine Empire and beyond. The Emperor Justinian, after whom the plague came to be named, had spent much of his reign beating back the Ostrogoths, Vandals, Berbers, Franks, Slavs, and Avars, in his attempts to restore the glory of the Roman Empire. It’s probable that the military supply trains, particularly in the shipments of grain, were excellent means of transmission for the rats and fleas carrying the plague. To make matters worse, the outbreak came soon after a series of volcanic eruptions had dimmed the sun, affecting crop yields across Europe. The population, already afflicted by the ravages of war, hunger, and half a decade of unseasonal cold, were in no position to resist a pestilence too.
We know now that the plague didn’t have its origins in Africa, like the Byzantines thought. Instead the plague had been carried to the Great Lakes region across the Indian ocean via merchant ships from Asia, where it had been devastating the continent for years. In 2018, scientists detected a strain of Yersinia pestis basal to the Justinian plague in the DNA of steppe nomads in Central Asia, suggesting that this outbreak had its origins in that plague basin too. It’s been conjectured, though not yet confirmed, that the Hun migrations of the fourth and fifth centuries might have had a hand in spreading the pestilence from the Eurasian steppe into Europe. This might explain the presence of the plague that has been detected in the remains of early Anglo-Saxons in Edix Hill, Cambridge, buried before the plague had reached Byzantium. This suggests a second transmission route into Europe, perhaps via the Baltic.
All told, some 50 million people were killed by the Justinian Plague — roughly half of the world’s population. But even this was not the first time Yersinia pestis had wrecked havoc upon the human populations of Eurasia.
Agriculture was introduced to Europe sometime in the 7th millennium BC by farmers from Anatolia. The spread of farming practices was followed by population growth and technological innovation, like pottery, the wheel, and metallurgy. This allowed the rise of trading networks for the first time, and for increasingly dense settlements. In the region that today encompasses Romania, Ukraine, and Moldova, the Trypillia Culture was able to build enormous settlements that could host as many as 10,000-20,000 residents. Archaeological evidence from these sites suggests humans and animals living close together in high densities. While this was no doubt a usual source of food and nutrients for the human population, it would also have created ideal conditions for disease transfer.
Curiously, the mega-settlements of the Trypillia culture suddenly disappear from the archaeological record around 5400 years ago. In fact, populations decrease all across Northern Europe to such an extent that the period has become known in the field as the Neolithic Decline. Recent DNA evidence has suggested a possible answer: Yersinia pestis.
In 2018, a team of researchers found ancient traces of the plague bacterium in 4900-year old remains in Sweden. A few years later, traces of the bacterium were found in a 5000-year old skull in Latvia. It was tentatively suggested that these finds correlate with the Neolithic Decline, and might explain the large die off within these farming societies. However the cases were isolated, with some of the infected buried with uninfected, suggesting there wasn’t an epidemic comparable to the Black Death outbreaks that would come in later millenniums.
However, a recent paper published only a few weeks ago has revealed a much greater prevalence of the pestilence. The DNA of 108 individuals from Scandinavia dating from 5300-4900 BP has revealed a Yersinia pestis infection rate of some 17% — an extraordinarily high number. The researchers have pieced together a story of a multi-generational plague that infected the population in three different outbreak events. As the bacterium was found in the deceased’s teeth, it’s highly likely it’s what killed them. The scientists suspect that Yersinia pestis hadn’t yet acquired the ability to transmit via fleas, but was instead spread by aerosol transmission, like covid or the flu, though it’s also possible that human lice might have carried the disease instead.
Within a few centuries, the Neolithic peoples of Europe were almost entirely replaced by a new people. These newcomers have their origins in the Pontic grasslands of the Dneiper basin at the far western edge of the Eurasian steppe. I wonder if, as steppe pastoralists, they had a higher resistance to the plague, which had so often emerged from the same region. Such questions are yet to be answered definitively.
Whether the Neolithic Decline was mostly, or in part, caused by the plague is still up for debate, but one thing is clear: humanity has been battling Yersinia pestis for a long, long time.
That’s the upper limit estimate. Historians disagree about the death toll, with huge variance.
This story might well have been fabricated in order to associate the plague with pagan barbarians, and thus attribute the devastation as punishment for godlessness. It’s perfectly possible that the plague spread from the besiegers to the besieged by the ordinary transmission vector: fleas on rats.
It wouldn’t be the last time either. For centuries after the 14th-century pandemic, plague continued to break out in smaller regional outbreaks. Between 1665 and 1666, 100,000 of London’s population were killed by the plague, and in the latter half of the 19th-century the third great Black Death pandemic in history swept from the remote province of Yunnan in China, down through Asia, into India, and even to Australia, killing 15 million people over five decades. Even today, in a world of antibiotics, Yersinia pestis continues afflicting people in Africa, South America, and Asia, with a fatality rate of 5-15%.
Interestingly, the anthropologist Wendy Orent has argued that the first trace of the bubonic plague in the written record is actually found in the Old Testament, which relates how the Philistines returned the Ark of the Covenant to the Israelites because they had been afflicted with mysterious “swellings”. Divine punishment or Yersinia pestis?
Notes
Bauer, Susan Wise (2013). The History of the Renaissance World
Frankopan, Peter (2015). The Silk Roads
Frith, John (2012). “The History of Plague – Part 1. The Three Great Pandemics”, in Journal of Military and Veterans Health Vol 20. No. 2.
Le Page, Michael (2024). “The plague may have wiped out most northern Europeans 5000 years ago”, in New Scientist (2024)
Sarris, P. (2021). “New Approaches to the ‘Plague of Justinian”, in Past & Present (2021).
Schmid, Boris; et al (2015). “Climate-driven introduction of the Black Death and successive plague reintroductions into Europe”, in Proc Natl Acad Sci USA, Vol 112 (2015).
Seersholm, F.V.; Sjögren, KG.; Koelman, J.; et al. (2024) “Repeated plague infections across six generations of Neolithic Farmers.” Nature 632, 114–121 (2024).
Spyrou, Maria A.; et al (2022). “The source of the Black Death in fourteenth-century central Eurasia”, in Nature 606, pages 718–724 (2022).
A continuation of the Justinian Plague: The Plague of Amwas, hit greater Syria in 638, just as the Muslim conquest was in full swing. It took out tens of thousands in the army camps and local populations. Significantly, it killed many of the Muslim leadership, including Yazid ibn Abi Sufyan. This resulted in his brother’s appointment as the new commander of the army in Syria: Mu’awiya ibn Abi Sufyan. Later, as govenor of Damascus, he contested the caliphate of Ali, leading to the Sunni/Shia split. Mu'awiya eventually became Caliph himself—the beginnings of the Umayyad Caliphate.
All because of a wee flea.
Here in Venice we still celebrate the end of two waves of plague. In July there are the festive celebrations of Redentore that finish with an hour of fireworks at midnight and in November is the solemn usually foggy day of Salute when we eat Castradina in honor of the Dalmatians that fed the city when it was cut off from the world.